Prototypes or prototypical instances combine the most representative attributes of a category. They are the best examples among the members of a category and serve as benchmarks against which the surrounding "poorer" instances are categorized (see Prototype (linguistics)).

A prototype can also refer to a test machine, circuit or program which is designed for demonstration purposes. It also enables the testing of the new product's design before the product is put into production. Problems or deficencies in the product's design can be discovered and corrected. When the prototype is sufficiently refined and meets the functionality, robustness, manufacturability and other design goals, the product is ready for production. Often such prototypes are built using techniques different than techniques for mass production -- see prototyping.

See also: Categorization, Semantics

Computer Science

In computer science, a prototype is the object-class combination that prototype-based programming is based on. Rarely, the declaration of a subroutine is also described as a prototype.

Model Railroads

Among model railroad enthusiasts, at least in North America, actual railroads are commonly spoken of as "prototypes".